function Lav = logMean(img, delta)
%
%
%        Lav = logMean(img, delta)
%
%       This function computes the geometric mean.
%
%        Input:
%           -img: an single channel image
%
%        Output:
%           -Lav: the logarithmic mean of img
% 
%     Copyright (C) 2010-13 Francesco Banterle
%  
%     This program is free software: you can redistribute it and/or modify
%     it under the terms of the GNU General Public License as published by
%     the Free Software Foundation, either version 3 of the License, or
%     (at your option) any later version.
% 
%     This program is distributed in the hope that it will be useful,
%     but WITHOUT ANY WARRANTY; without even the implied warranty of
%     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%     GNU General Public License for more details.
% 
%     You should have received a copy of the GNU General Public License
%     along with this program.  If not, see <http://www.gnu.org/licenses/>.
%

if(~exist('delta', 'var'))
    delta = 1e-6;
end

img_delta = log(img + delta);

Lav = exp(mean(img_delta(:)));

end